Rotary electrical coupling

ABSTRACT

There is disclosed a rotatable coupling for electrical cables which utilizes a tulip connector in which the opposed ends of two cylindrical conductors are rotatably journalled. The coupling is disclosed in conjunction with a dangler cathode cable wherein the wire conductor portion and the sheath portion are both securely connected at one end of the cable to one of the conductors within the tulip connector and at the opposite end of the cable to a ball-like cathode member. The rotatable coupling is also disclosed for use on a reel for a magnetic hoist where two rotatable couplings are concentrically arranged one within the other to electrically couple two cables on the reel driven with potentials of opposite polarity from a source of power.

[4 1 Oct. 14, 1975 ABSTRACT Primary ExaminerRichard E. Moore Attorney, Agent, or Firm-Bames, Kisselle, Raisch & Choate There is disclosed a rotatable coupling for electrical cables which utilizes a tulip connector in which the opposed ends of two cylindrical conductors are rotatably joumalled. The coupling is disclosed in conjunction with a dangler cathode cable wherein the wire conductor portion and the sheath portion are both securely connected at one end of the cable to one of the conductors within the tulip connector and at the op- United States Patent Kinnear 1 ROTARY ELECTRICAL COUPLING [76] Inventor:

[22] Filed:

15 Claims, 13 Drawing Figures posite end of the cable to a ball-like cathode member. The rotatable coupling is also disclosed for use on a reel for a magnetic hoist where two rotatable couplings are concentrically arranged one within the other to electrically couple two cables on the reel driven with potentials of opposite polarity from a a. o n. m 9 8 9 f O 1 ll a 3 u L. s w 4 3 Ir. J mmvmu va "H 4 r n 4. I s Z/ 00 00 wmmmm w Clive 36555 23 4 SSSSNW. QQQQOAJ wwwwn o w M 4 n .n 2 3333 A mm 4 0 6 mm mWL mwmm M MR n. mm "mo Swan" ad m wmmmmm a mooa en T 72224A2O 5666 66 99999 99 HHHHHNHH H HH GW E O3662 37 63229049 ,F 76447 58 40662 78 J 98 2333 US. Patent oct.14,19'75 sheetzom 3,912,352

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US. Patent Oct. 14, 1975 Sheet 3 of4 3,912,352

US. Patent OCt. 14, 1975 7 FIG. 12 I;

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ROTARY ELECTRICAL COUPLING This invention relates to electrical couplings of the rotatable type.

In many types of apparatus supplied with electrical power there arises the necessity for establishing an electrical connection between a stationary terminal member and an operating member which is designed to rotate or which in use has a tendency to rotate. An example of an apparatus where the operating member rotates is a cable reel for a magnetic hoist. In such a hoist a high amperage cable is wound on a drum and is reeled on and off of the drum as the magnet is raised and lowered. One end of the cable is connected to the magnet and the other end of the reel is connected to collector rings on the drum which, through brush contacts, are connected to a source of electrical power. In such an arrangement it is desirable that electrical connection is designed for economical production and it is essential that the electrical connection is capable of carrying large currents and is readily serviceable.

An example of an apparatus where the operating member has a tendency to rotate is a dangler cable in a rotating plating barrel wherein the cathode is in the form of a metal ball-like member connected to one end of a dangler cable extending axially into the plating barrel through one end thereof. While such dangler cables of conventional construction are not designed to rotate, nevertheless it frequently happens that the cathode ball-like member at the free end of the cable becomes entangled with workpieces tumbling in the rotating barrel. Under such circumstances the outer rubber or neoprene sheath around the cable tends to flex and twist more readily than the copper wire strands within the sheath. As a result, the wire strands become twisted and knotted and in a relatively short period of time this leads to destruction of the cable.

The primary object of the present invention is to provide a rotatable electrical connection of economical construction which is designed to carry high currents and which is also designed to facilitate servicing thereof.

A more specific object of the present invention is the provision of a rotary electrical coupling for high amperage cables which is admirably suited for electrically connecting a cable to a fixed terminal while enabling the cable to rotate about its longitudinal axis.

Another object of the invention resides in the provision of a dangler cable construction for plating barrels which is designed not only to rotate relative to the terminal to which it is connected but also to withstand the torque to which such dangler cables are subjected when they become entangled with workpieces tumbling in the rotating plating barrel.

In general, the present invention contemplates a rotatable coupling which comprises a pair of opposed, rigid, coaxially aligned, cylindrical, electrical conductors, one of which is fixed and the other is rotatable, with an electrical tulip connector circumscribing the opposed ends of the conductors, The petals of the tulip connector frictionally engage the outer cylindrical surface of the two conductors to establish good electrical contact therebetween while permitting relative rotation of the two conductors.

More specifically, in connection with a rotatable cable coupling the invention contemplates a sheathed cable capable of carrying a relatively high electrical load and also capable of transmitting torque axially from one end of the cable to the other. The ability to transmit the'axial torque is achieved primarily by the fact that the rubber or neoprene sheath is bonded directly to the outer strands of the wire conductors which, as is conventional in such cables, are spirally wound lengthwise of the cable in individual groups. However, in a conventional cable there is interposed a paper, mylar or other laminating strip between the sheath and the wire strands. This laminating strip facilitates stripping the opposite ends of the sheath material from the wire strands since it forms a separator therebetween but at the same time it permits the sheath to twist axially somewhat independently of and to a greater extent than the inner wire strands.

In the cable construction of the present invention fittings are provided at the opposite ends thereof which are integrally connected to both the sheath and the wire strands. One of these fittings incorporates a tulip connector which enables the fitting to rotate relative to a fixed terminal to which the fitting is electrically connected. In the case of a dangler cable for plating barrels the fitting at the other end thereof comprises a ball-like cathode member.

Other objects and features of the present invention will become apparent from the following description and drawings, in which:

FIG. 1 is a fragmentary side elevational view, partly in section, of a plating barrel arrangement employing a rotatable electrical coupling and dangler cables constructed in accordance with the present invention;

FIG. 2 is a fragmentary sectional view along the line 2-2 in FIG. 1;

FIG. 3 is an elevational view, partly in section, of the rotatable end of the dangler cable illustrated in FIG. 1; FIG. 4 is a sectional view along the line 44 in FIG.

FIG. 5 is a perspective view of one of the tulip petals of the tulip connector illustrated in FIG. 2;

FIG. 6 is a sectional view along the line 6-6 in FIG.

FIG. 7 is a fragmentary view, partly in section, showing the cathode end of the dangler cable illustrated in FIG. 1 in the assembled condition;

FIG. 8 is an elevational view, partly in section, showing the sleeve by means of which the cable is connected to the ball-shaped cathode member;

FIG. 9 is a fragmentary sectional view illustrating the manner in which the cable, sleeve and cathode are assembled;

FIG. 10 is a fragmentary elevational view illustrating the manner in which the sleeve shown in FIG. 8 is staked to the cable sheath;

FIG. 1 l is a fragmentary sectional view of a cable reel embodying the rotatable coupling of the present invention;

FIG. 12 is a fragmentary sectional view of another modification of rotatable electrical coupling of this invention; and

FIG. 13 is a fragmentary sectional view of a further modified form of a rotatable electrical coupling of this invention.

In FIG. 1 certain features of the present invention are illustrated in connection with a plating tank which is generally designated at 10. Within the tank there is suitably supported for rotation a plating barrel l2 having end walls 14 and perforated side walls 16. In the arrangement illustrated barrel 12 is supported by one or more yokes 18 and is rotated about its longitudinal axis by means of a drive mechanism, including a gear 20 attached to one of the end walls of barrel l2. Barrel 12 is provided with an apertured bushing 22 at each end thereof which is located at the axis of rotation of the barrel. A dangler cable 24 extends through the apertured bushings 22. At the end of each cable 24 within barrel 12 there is secured a stainless steel ball-shaped cathode member 26 and the opposite end of each dangler cable is connected to a bus bar 28 by means of a rotatable coupling 30. In this arrangment when barrel 12 is rotated there is always the possibility of either cathode 26 becoming entangled with the workpieces 32 being plated, but the construction of the cable and of coupling enables the cable as a whole to twist or rotate about its longitudinal axis.

Referring now to FIG. 2, the cable includes an outer sheath 34 formed of rubber, neoprene or the like and a multitude of spirally wound copper wires 36 within sheath 34. No attempt has been made to show wires 36 according to their actual size. For example, a cable embodying the present invention would have an outer diameter of at least about /2 inch; the bundle of copper wires would have a diameter of at least about /8 inch; and the individual wire strands would be at least three or four thousand in number. As pointed out above, in a conventional cable of this type a laminating strip is normally employed between wires 36 and outer sheath 34. However, in the cable of the present invention sheath 34 is bonded directly to the outer stands of wires 36 so that there is no tendency for the sheath to twist or rotate axially relative to the wire strands.

In the arrangement shown in FIG. 2 sheath 34 is stripped from each end of the cable so as to expose the length of the wire strands as indicated at 38. At one end of the cable a copper sleeve is mechanically shrunk on the stripped ends 38 of wire strands 36 so as to provide a firm mechanical connection between the wire strands and one end of the sleeve. The opposite end of sleeve 40 is mechanically staked to a stainless steel cup 42 which is in turn securely crimped as at 44 to sheath 34 so as to provide a rigid non-rotatable connection between sleeve 40 and sheath 34. The annular hump 46 on sleeve 40 is provided to facilitate shrinking the sleeve on the wire and staking cup 42 thereon in nonrotatable manner.

Referring now to FIG. 7, the opposite end of cable 24 is connected to the ball-shaped cathode member 26 by a sleeve 48. The end of the cable associated with cathode 26 is likewise stripped of sheath 34 to expose the wire strands 38. To form an assembly of cathode 26, sleeve 48 and the stripped end of the cable, the wire strands 38 are first inserted through the cylindrical bore 50 ofa stainless steel sleeve 48 so that they project outwardly beyond the end thereof as at 52. The enlarged bore 54 is sized to receive the end portion of sheath 34 adjacent the stripped wire strands 38. The upper end of bore 54 is rounded around its periphery as at 56. After the wire strands 38 are inserted through sleeve 48 the sleeve is inserted in the tapered bore 58 of cathode 26. The outer periphery of sleeve 48 is correspondingly tapered as at 60. However, the dimensions of the tapered portion 60 of sleeve 48 and the tapered bore 58 of cathode 26 are related such that sleeve 48 can be manually inserted into bore 58 only to the extent shown in FIG. 9. The full insertion of sleeve 48 into cathode 26 is accomplished by means of a ram plate 62 to a press which bears against the upper end of sleeve 48 and by means of downward pressure causes the tapered portion 64 of the sleeve to be circumferentially ensmalled and, thus, shrunk firmly onto the stripped wires 38 of the cable as the sleeve is forced axially downwardly into tapered bore 58 from the position shown in FIG. 9 to that shown in FIG. 7. The taper on sleeve 48 and within the bore of cathode 26 is such that when the sleeve is driven to the position shown in FIG. 7 it is not only rigidly and permanently connected to cathode 26, but it is also firmly and rigidly connected to the bundle of wire strands 38. If desired, an upwardly tapered protrusion 66 may be provided at the lower end of bore 58 for spreading the wire strands as at 52 to insure positive retention of the wire strands within sleeve 48. The assembly is completed in the manner shown in FIG. 10 where a die 68 having a suitable rounded cavity 70 is forced downwardly over the upper enlarged end of sleeve 48 to crimp the rounded portion 56 firmly onto the cable sheath 34 to effect a permanent non-rotatable connection therebetween. The rounded edge portion 56 prevents the sleeve from shearing sheath 34 when the sleeve is crimped to the cable.

Returning now to FIG. 2, one form of rotatable coupling of this invention is illustrated in detail. This coupling, generally designated 30, includes a first tubular conductor 72, perferably formed of copper, flattened at one end as at 74 for connection to bus bar 28 as by means of a nut and bolt assembly 76. The opposite end of tubular conductor 72 is flared outwardly as at 78. Coupling 30 includes a second tubular copper conductor co-axially arranged with tubular conductor 72 and with its adjacent end likewise flared outwardly as at 82. The other end of tubular conductor 80 is provided with a pair of axially aligned apertures 84.

The juxtaposed flared ends 78,82 of the two tubular members 72,80, respectively, are encircled by a tulip connector 86. Tulip connector 86 is of the type disclosed in my copending application Ser. No. 245,138,

filed Apr. 18, 1972, now US. Pat. No. 3,813,638, and

includes a plurality of petals 88 formed of an electrically conductive material, such as copper. Petals 88 are arranged in circumferential fashion around tubular members 72,80 and extend lengthwise thereof. The opposite ends of petals 88 flare outwardly as at 90 and intermediate portion of each petal forms an outwardly extending hump 92 which encircles the outwardly flared ends 78,82 of tubular conductors 72,80, respectively. As shown in FIG. 2, this configuration of petals 88 provides annular saddles for the reception and retention of coil garter springs 94 adjacent opposite ends of petals 88. Petals 88 are also slightly curved in transverse section as generally indicated at 96 in FIGS. 4 and 5 so that at one end each petal 88 has two points of contact with the outer cylindrical surface of conductor 72 and at the opposite end each petal has two points of contact with the outer cylindrical surface of conductor 80.

In the assembled condition of the coupling the side edges of petals 88 are spaced apart slightly. Springs 94 provide a circumferential tensioning means around the series of petals 88 so as to urge them radially inwardly and, thus, provide a good electrical connection between each petal 88 and conductors 72,80. Thus the coupling provides a good electrical connection between conductors 72,80 while at the same time permitting relative rotation therebetween. The flared ends 78,82 of the conductors extend into the groove formed by the humps 92 on petals 88 and, thus, prevent tubular members 72,80 from being axially withdrawn from within the tulip connector. However, tubular member 80 is free to rotate axially relative to the tubular member 72 connected to bus bar 28.

In the case of a plating dangler where the coupling might be subjected to corrosive acids and fumes it is desirable to encapsulate the entire coupling by a heat shrinkable plastic cover 98. In this event a pair of plastic washers 100 are employed at the opposite ends of the tulip connector which have a slip fit on conductors 72,80. Cover 98 also has a slip fit with tubular member 80.

The copper sleeve clamped on the end of cable 24 is detachably, but non-rotatably, connected with conductors 80. This connection can be made utilizing the electrical connector 102 disclosed in my copending application Ser. No. 273,691, filed July 21, 1972, now abandoned. Generally speaking, connector 102 comprises a stainless steel tubular element having a generally cylindrical cross section and formed from a straplike member having curvilinear overlapping end portions 104,106. The overlapped end portions 104,106 are threaded to receive clamping screws 108. Screws 108 register axially with openings 84 in tubular member 80 so that when connector 102 is slipped over the free end of tubular member 80 screws 108 can be advanced through openings 84. Sleeve 40 is dimensioned to be received with a close fit within tubular member 80 so that when screws 108 are tightened sleeve 40 is rigidly and non-rotatably connected to tubular member 80. Screws 108 can be tightened to an extent sufficient to produce indentations 110 in sleeve 40 without stripping the threads in the openings of the overlapped ends 104,106 of connector 102. This is described in my said copending application Ser. No. 273,691.

With the arrangement thus described it will be appreciated that, if the cathode members 26 at the free ends of cables 24 become entangled with workpieces 32 in plating barrel 12, they will have a tendency to rotate. Since the rubber sheath 34 forms the outer diameter of the cable and since each cathode member 26 is se- "rely connected to both sheath 34 and wire strands the torque resulting from the tendency of cathodes L to rotate is transmitted lengthwise of the cable to the other end thereof with little or no tendency to twist axially. In this respect the cable transmits torque as an integral member since sheath 34 is bonded to the wire strands 36. As this torque is transmitted to coupling 30, tubular conductor 80 rotates freely relative to tubular conductor 72 while maintaining a good electrical connection therebetween. This is enhanced by the fact that tubular sleeve 40 is rigidly connected to tubular member 80, to wire strands 38 and also to the cable sheath 34.

It will be appreciated that, while the present invention has been described in connection with a dangler cable for a plating barrel, the invention is also admirably suited for numerous other uses where a rotatable electrical connection may be desired. For example, in the case of portable industrial welders where the welder heads are connected to a power source by long heavy cables, the cables tend to wind up and twist as they are pulled from one location to another. The cable and rotatable coupling described herein is admirably suited for use on such welder cables and any other types of cables which in use are subjected to twisting about their longitudinal axes.

As previously indicated, the rotatable electrical coupling of this invention is admirably suited for establishing an electrical connection in various types of apparatus where a rotating member must be electrically connected to a fixed member. In FIG. 11 there is illustrated another application of the present invention in connection with a cable reel or drum which might be used on a hoist employing a magnet as the lifting member. In such an arrangement the magnet is connected by a suitable two conductor cable to a power source and the cable has to be extended and retracted as the magnet is raised and lowered. In the arrangement illustrated in FIG. 11 the two conductor cable is designated 112 and is wound on a drum 1 14 supported by a bearing 1 16 for rotation on a molded insulating hub 118 fixedly mounted on a support 120. Within hub 118 the coupling of the present invention is arranged. In this particular arrangement the coupling includes concentric tubular conductors 122,124. The two conductors of cable 112 are connected one to conductor 122 as at 126 and the other to conductor 124 as at 128. Tubular conductor 122 is press fitted into an insulating disc 130 which is mounted on the end wall 132 of drum 114 by bolts 134. Tubular conductor 124 is press fitted into an insulating sleeve 136 which is in turn press fitted in disc 130.

Hub 118 has molded integrally therewith or press fitted thereinto a pair of tubular conductors 138,140. Conductors 122,124,138,140 are concentrically arranged with the adjacent ends of conductors 122 and 138 and the adjacent ends of conductors 124 and 140 in axially spaced apart opposed relation. The inner ends of conductors 138,140 are preferably flared radially outwardly as at 142. On the other hand, since it may become necessary to remove drum 114 from support 120 the inner ends of conductors 122,124 preferably extend as smooth cylindrical surfaces. The axially aligned opposed ends of conductors 122,138 are circumferentially circumscribed by a tulip connector 144 and the axially aligned opposed ends of conductors 124,140 are circumferentially circumscribed by a tulip connector 146. Tulip connectors 144,146 are generally of the same construction as tulip connector 86, previously described. In the manner described previously tulip connector 144 forms a good electrical connection between conductors 138 and 122 and tulip connector 146 forms a good electrical connection between conductors 140 and 124. At the same time these tulip connectors permit relative rotation between drum 114 and the fixed support 120. Thus the two tulip connectors function in the manner of electrical collector rings.

Since in an arrangement of this type drum 114 rotates more or less constantly relative to support 120, in the arrangement shown in FIG. 11 the tubular conductors should be very accurately sized around their outer periphery and finished with a smooth surface from an electrically conducting material (such as stainless steel or the like) which is capable of withstanding the wear resulting from such relative rotation. Conductors 138,140 are connected to a power source as by conductors 148,150, respectively. A tubular insulating sleeve 152 is molded with or press fitted into hub 118 and forms an electrical insulating sleeve between the concentric tulip connectors 144 and 146.

FIG. 12 illustrates a further modification of the rotatable electrical coupling of the present invention. In this arrangement a tubular conductor 154 is welded or otherwise secured to a bus bar 156. The free end of conductor 154 is flared outwardly as at 158. A second tubular conductor 160 is arranged with one end in axially opposed relation to the flared end 158 of conductor 154. The end of conductor 160 is bulged slightly as at 162 and has a radially inwardly extending rounded surface portion 164 at its extreme end. The bulged portion 162 of conductor 160 and the flared end 158 of conductor 154 are circumferentially circumscribed by a tulip connector 166. In this arrangement the end portion 162,164 of conductor 160 is sized such that it can be snapped into and out of engagement with tulip connector 166 to provide a detachable, rotatable electrical connection between conductors 154 and 160.

The coupling illustrated in FIG. 13 is similar in many respects to the coupling illustrated in FIG. 2; it includes a pair of axially opposed tubular conductors 168,170 having their inner opposed ends outwardly flared as at 172. These flared ends are circumscribed by a tulip connector 174 to provide a rotatable electrical connection between conductors 168,170. In order to insure against axial separation of conductors 168,170 a pair of stainless steel cups 176,178 are arranged over each end of tulip connector 174 to enclose the garter springs 94. In the event of an axial pull on either conductor 168 or conductor 170 cups 176,178 will prevent the corresponding end of the tulip connector from circumferentially enlarging to permit the retraction of the flared end 172 of the conductors. Cups 176,178 are held in place by a molded insulating cover 180. Prevention of circumferential expansion of the tulip connector may be further assured by locating a circumferentially continuous ring 182 between the two garter springs and around the outwardly curved central portions of the tulip petals. The opposite ends of ring 182 extend within cups 176,178. Thus, with the arrangement shown in FIG. 13 in order to axially separate conductors 168,170 a sufficient axial force must be applied thereto to straighten out the flared end 172 of either of the conductors.

It will be understood that the couplings shown in FIGS. 12 and 13 are used for a cable connection, the cable could be connected thereto in the manner illustrated in FIG. 2. However, if the arrangement does not require the cable to be detachably connected to one of the conductors of the coupling, then the connector sleeve shown at 102 in FIG. 2 could be eliminated and the tubular conductor of the coupling could be connected directly to the cable in the manner illustrated by sleeve 40 and cup 42 in FIG. 2.

In other words, conductor 80 can be mechanically shrunk directly on the stripped end 38 of the cable and its outer end staked to the adjacent edge of cup 42.

I claim:

1. In combination, an electrical cable comprising an outer sheath enclosing wire strands, one end of said cable having said sheath stripped therefrom, a first cylindrical electrical conductor fixedly and nonrotatably secured to said sheath at said one end of said cable and circumscribing in clamped relation said stripped end of the wire strands in electrically conducting relation thereto, an electrical terminal having a second cylindrical electrical conductor nonrotatably connected thereto, said two conductors having generally the same outer diameter and being axially aligned in opposed relation with their adjacent ends adjacently positioned, a circumferentially resilient connector sleeve encircling said opposed ends of said two conductors and in frictional electrical contact with the outer cylindrical surfaces thereof, said cable being flexible and rotatable and having sufficient torsional resistance to transmit torque to said first conductor when torque is applied to the cable at a section remote from said first conductor, said first conductor being disposed within said sleeve such that, except for said frictional contact, said first conductor is freely rotatable relative to the second conductor whereby to permit the cable to rotate about its axis relative to said terminal.

2. The combination set forth in claim 1 including means rotatably interengaging at least one of said tubular conductors with said sleeve to prevent axial separation thereof.

3. The combination set forth in claim 1 including means rotatably interengaging each of said conductors with said sleeve to prevent axial separation thereof.

4. The combination set forth in claim 1 wherein said sleeve is bowed radially outwardly intermediate the opposite ends thereof and the adjacent ends of both conductors are tubular and flared radially outwardly to interengage with the radially outwardly bowed portion of said sleeve to prevent said axial separation thereof.

5. The combination set forth in claim 1 wherein said connecting sleeve comprises a series of petals formed of electrically conductive metal, said petals being of ar cuate shape in longitudinal section and being arranged in circular fashion with their side edges extending longitudinally of said sleeve, said petals defining a radially outwardly facing annular groove adjacent opposite ends of the sleeve, resilient means circumscribing said sleeve adjacent each end thereof and disposed within said groove to circumferentially contract the opposite ends of said petals around the opposite end portions of the two conductors.

6. The combination set forth in claim 5 wherein said petals are of arcuate shape in transverse section at the grooved portion thereof and each presenting a concave surface portion to the outer surface of said conductors which has a radius of curvature different from the radius of curvature of the outer surfaces of said conductors.

7. The combination set forth in claim 6 including a non-conducting cover circumferentially enclosing said sleeve and the adjacent portions of said tubular conductors to seal the rotatable connection therebetween.

8. The combination set forth in claim 1 wherein the opposite end of said cable has a cathode member secured thereto, said cathode member being of substantially larger diameter than said cable.

9. The combination set forth in claim 8 wherein said sheath is bonded to the outermost wire strands of the cable and said cathode and first-mentioned tubular conductor are securely and non-rotatably connected to said wire strands and sheath whereby said sheath and wire strands cooperate to form an integral member for transmitting torque from one end of the cable to the other in the event the cathode has a tendency to rotate.

10. The combination set forth in claim 1 wherein said sheath is bonded to the outermost wire strands of the cable and said first-mentioned tubular conductor is securely and non-rotatably connected to both said wire strands and said sheath.

11. The combination set forth in claim 1 including radial enlargements on the opposed ends of said conductors which interengage with said sleeve, said enlargements causing said sleeve to circumferentially expand when the conductors are subjected to a force tending to cause axial separation of the conductors and sleeve, and means circumscribing said sleeve to prevent circumferential expansion thereof to an extent sufficient to allow withdrawal of the enlarged ends of the conductors from within said sleeve in response to an axial outward force on the conductors.

12. The combination set forth in claim 11 wherein said sleeve comprises a series of petals formed of electrically conducting material, said petals being arranged in circular fashion with their side edges extending longitudinally of said sleeve, and spring means circumferentially circumscribing said petals to circumferentially contract the same around the ends of the conductors, said expansion preventing means comprising means extending circumferentially around said spring means.

13. The combination set forth in claim 12 wherein said spring means comprises a pair of axially spaced, circumferentially expandable springs circumscribing the opposite ends of said sleeve and said expansion preventing means comprising a pair of cup-shaped mem bers extending around said springs with their open ends in opposed relation, the axially outer ends of said cupshaped members being centrally apertured to accommodate said conductors.

14. The combination set forth in claim 13 including a relatively nonelastic ring circumscribing said petals around the axial central portion thereof and disposed between said springs, said ring having an axial dimension greater than the axial spacing between the open ends of said cup-shaped members.

15. The combination set forth in claim 14 wherein said ring is disposed within said cup-shaped members with its inner periphery spaced closely adjacent the outer periphery of said sleeve in the axial central portion thereof and its inner periphery spaced closely adjacent the inner periphery of said cup-shaped members. l= 

1. In combination, an electrical cable comprising an outer sheath enclosing wire strands, one end of said cable having said sheath stripped therefrom, a first cylindrical electrical conductor fixedly and nonrotatably secured to said sheath at said one end of said cable and circumscribing in clamped relation said stripped end of the wire strands in electrically conducting relation thereto, an electrical terminal having a second cylindrical electrical conductor nonrotatably connected thereto, said two conductors having generally the same outer diameter and being axially aligned in opposed relation with their adjacent ends adjacently positioned, a circumferentially resilient connector sleeve encircling said opposed ends of said two conductors and in frictional electrical contact with the outer cylindrical surfaces thereof, said cable being flexible and rotatable and having sufficient torsional resistance to transmit torque to said first conductor when torque is applied to the cable at a section remote from said first conductor, said first conductor being disposed within said sleeve such that, except for said frictional contact, said first conductor is freely rotatable relative to the second conductor whereby to permit the cable to rotate about its axis relative to said terminal.
 2. The combination set forth in claim 1 including means rotatably interengaging at least one of said tubular conductors with said sleeve to prevent axial separation thereof.
 3. The combination set forth in claim 1 including means rotatably interengaging each of said conductors with said sleeve to prevent axial separation thereof.
 4. The combination set forth in claim 1 wherein said sleeve is bowed radially outwardly intermediate the opposite ends thereof and the adjacent ends of both conductors are tubular and flared radially outwardly to interengage with the radially outwardly bowed portion of said sleeve to prevent said axial separation thereof.
 5. The combination set forth in claim 1 wherein said connecting sleeve comprises a series of petals formed of electrically conductive metal, said petals being of arcuate shape in longitudinal section and being arranged in circular fashion with their side edges extending longitudinally of said sleeve, said petals defining a radially outwardly facing annular groove adjacent opposite ends of the sleeve, resilient means circumscribing said sleeve adjacent each end thereof and disposed within said groove to circumferentially contract the opposite ends of said petals around the opposite end portions of the two conductors.
 6. The combination set forth in claim 5 wherein said petals are of arcuate shape in transverse section at the grooved portion thereof and each presenting a concave surface portion to the outer surface of said conductors which has a radius of curvature different from the radius Of curvature of the outer surfaces of said conductors.
 7. The combination set forth in claim 6 including a non-conducting cover circumferentially enclosing said sleeve and the adjacent portions of said tubular conductors to seal the rotatable connection therebetween.
 8. The combination set forth in claim 1 wherein the opposite end of said cable has a cathode member secured thereto, said cathode member being of substantially larger diameter than said cable.
 9. The combination set forth in claim 8 wherein said sheath is bonded to the outermost wire strands of the cable and said cathode and first-mentioned tubular conductor are securely and non-rotatably connected to said wire strands and sheath whereby said sheath and wire strands cooperate to form an integral member for transmitting torque from one end of the cable to the other in the event the cathode has a tendency to rotate.
 10. The combination set forth in claim 1 wherein said sheath is bonded to the outermost wire strands of the cable and said first-mentioned tubular conductor is securely and non-rotatably connected to both said wire strands and said sheath.
 11. The combination set forth in claim 1 including radial enlargements on the opposed ends of said conductors which interengage with said sleeve, said enlargements causing said sleeve to circumferentially expand when the conductors are subjected to a force tending to cause axial separation of the conductors and sleeve, and means circumscribing said sleeve to prevent circumferential expansion thereof to an extent sufficient to allow withdrawal of the enlarged ends of the conductors from within said sleeve in response to an axial outward force on the conductors.
 12. The combination set forth in claim 11 wherein said sleeve comprises a series of petals formed of electrically conducting material, said petals being arranged in circular fashion with their side edges extending longitudinally of said sleeve, and spring means circumferentially circumscribing said petals to circumferentially contract the same around the ends of the conductors, said expansion preventing means comprising means extending circumferentially around said spring means.
 13. The combination set forth in claim 12 wherein said spring means comprises a pair of axially spaced, circumferentially expandable springs circumscribing the opposite ends of said sleeve and said expansion preventing means comprising a pair of cup-shaped members extending around said springs with their open ends in opposed relation, the axially outer ends of said cup-shaped members being centrally apertured to accommodate said conductors.
 14. The combination set forth in claim 13 including a relatively nonelastic ring circumscribing said petals around the axial central portion thereof and disposed between said springs, said ring having an axial dimension greater than the axial spacing between the open ends of said cup-shaped members.
 15. The combination set forth in claim 14 wherein said ring is disposed within said cup-shaped members with its inner periphery spaced closely adjacent the outer periphery of said sleeve in the axial central portion thereof and its inner periphery spaced closely adjacent the inner periphery of said cup-shaped members. 